P erformance Assessment of Passive Ga seous P rovisions (PGAP) - FRA 1

1. Performance Assessment of Passive Gaseous Provisions (PGAP) - FRA 1 Nicolas DEVICTOR (nicolas.devictor@cea.fr) Presented by Alfredo VASILE INPRO Consultancy Meeting 21-25 May 2007

2. Context From 2 IAEA activities: • CRP "Natural circulation phenomena, modeling and reliability of passive systems that utilize natural circulation • IAEA technical meeting "Status of Validation and Testing of Passive Systems for SMRs" (held in Vienna on June 2006), We note: • it exists different definitions for the thermal-hydraulic passive system reliability and different assessment methodologies (as for instance 5th PCRD RMPS, MIT/CANES methodology, APSRA (India)…). • There is not a consensus on the definition of the thermal-hydraulic passive system reliability (“performance” seems a better term) : is it possible to allot an intrinsic reliability to a thermal-hydraulic passive system ? or is it only possible to assess the probability of reaching an expected performance of this system for a given scenario? • Parts of the existing methodologies seems complementary and could be merged for obtaining a more consistent methodology at least for assessing the performance of a passive system for a given scenario. These questions are more and more important for advanced reactors (and particularly for GenIV concepts). INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)

3. Description of the proposal • Consequently the CEA proposes a benchmark in order to contribute on the consensual definition of the reliability of a Category B passive system, and on a methodology to assess this reliability. • The CRP will be based on a comparative analysis of the definitions of the thermal-hydraulic passive system reliability, on a comparison of the assessment methodologies and a comparison of computational results. • The first step (Activity 1) : • for 2 scenarios (situations pressurized and depressurized), the assessment of the probability that the expected performance of the thermal-hydraulic passive system is not reached, for a given initiating event and a configuration of the reactor (characterizing the situations). • The second step (Activity 2) : • to progress in a common methodology for assessing the “reliability” of a thermal-hydraulic passive system, • to propose, if possible, a common definition of the “reliability” of a thermal-hydraulic passive system. INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)

4. Description of the proposal • Main Output = TECDOC report including the following: • The definition of the benchmark; • The results obtained by each participant; • A comparative analysis; • A proposal for a common methodology for assessing the “reliability” of a thermal-hydraulic passive system; • A proposal for a common definition of the “reliability” of a thermal-hydraulic passive system. • Identification of necessary R&D. • Additional outputs will be the meeting reports. • Proposed schedule (duration of the CRP = 24 months) • T0: initial meeting (the CEA will present in detail the content of the benchmark); • T0 + 5 months: meeting with objective of finalizing the definition of the benchmark (taken into account of the comments and requests for clarification); • T0 + 15 months: intermediate meeting; • T0 + 22 months: meeting to discuss the results and to prepare a draft of the conclusions of CRP (last meeting– the TECDOC will be finalized by emails). INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)

5. Status of the benchmark definition • Study of the Decay Heat Removal (DHR) strategy in the GFR 2400 MWth for two situations: one pressurized and one depressurized. The DHR loops and strategy use active and passive systems according to the initiating events. • 2 documents describes the GFR 2400 MWth • “Contribution to GFR design option selection”, by J-C. Garnier et al. (Proceedings of ICCAP’06) • “The DHR Systems of the GFR, Preliminary Design and Safety Analysis”, by J-Y. Malo et al. (Proceedings of ICCAP’07) • Additional information will be provided as needed for the benchmark • The specification of the benchmark (description of 2 scenarios, definition of the uncertain quantities…) is the content of the CEA Technical report CEA/DEN/CAD/DER/SESI/LCFR/NT DO 3 08/03/07. • From a practical point of view, a CATHARE model is available in CEA for the calculation. Comment : Concerning the gas fast-cooled reactor with helium coolant, there is no available experimental data to our knowledge. Then parts of the APSRA methodology could not be studied in the frame of this CRP proposal. INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)

6. Project cost assessment • CEA part : 3 man.months per year. • Note: The CEA will not contribute a financial share to partners. It will be able to accommodate some meetings. • Other partners ? (see next slide) INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)

7. Potential partners • During the 10th INPRO Steering Committee Meeting (December 2006), 3 countries stated to be a priori interested : India, Spain and Belgium. • The PGAP proposal was sent for information and reply to : • USA : Professor George Apostolakis (MIT/CANES) • India : Mr. Ratan K. Sinha (BARC) • Spain : Mrs. Maria Teresa Dominguez (Empresarios Agrupados) • Belgium : Mr. Baudoin Arien and Mr. Peter Baeten (SCK.MOL) • Status at 14 May 2007 : no reply INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)

8. Relationships with other activities • Concerning the definition and the terminology, exchanges with the following groups will be useful: • Working Group Risk of the OCDE/NEA/CSNI carries out a technical follow-up of this topic (Nicolas Devictor is member of the WG) ; • GenIV Forum • The Risk and Safety Working Group (RSWG). • Projects on this topic within the framework of bilateral agreements between the countries involved in Gen IV exist or are under discussions. • IAEA CRP Proposal “Development of Advanced Methodologies for Substantiation of Passive System Performance in Advanced Reactors” • Some objectives of PGAP proposal and this CRP proposal are common, as for instance : • “To work out a consensus set of definitions relevant to reliability assessment of the passive systems and their treatment by PSA” • “To perform trial applications of various approaches to reliability assessment of selected benchmark problems, with evaluation of uncertainties” • “To identify a possible common approach and draft suggestions for further elaboration of IAEA Safety Standards” • “To identify necessary R&D” INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)

9. Alternative proposal If no country is interested by such benchmark (due to for instance to the GFR choice), As the CEA will do the work (it is necessary for the Level 1 PSA model under development in support to the GFR 2400 MWth design), France proposes to integrate in another CRP the on-going application by CEA as an example in support to a CRP work. For instance, this application seems to be useful for the CRP Proposal “Development of Advanced Methodologies for Substantiation of Passive System Performance in Advanced Reactors (1.1.5.4/12)” INPRO Consultancy Meeting 21-25 May 2007 – PGAP (FRA 1)